High viscosity starches using stannic chloride



United States Patent 3,1118% IHGH VISOSITY STARHES USING STANNICCHLGRIDE Qhim Patel, St. Louis, Mo., and Ronald E. Pyle, Granite City,IlL, assignors to Union Starch and Refining Company, ind, Columbus, ind,a corporation of Indiana No Brewing. Filed Apr. 6, 1961, Ser. No.101,073

Claims. {Cl. 127-33) The present invention relates generally to starchderivatives and more particularly to a novel high viscosity, Watersoluble starch product and to a novel method for producing it fromunmodified starch. Specifically, the present invention pertains to athick-boiling starch prepared from unmodified starch by reaction withstannic chloride.

An object of the present invention is to provide a modified starchproduct which gives higher viscosity pastes than unmodified starch whencooked either with Water or alkaline solutions.

A second object of this invention is to produce a modified starchproduct which gelatinizes at a lower temperature than common for theunmodified starch from which it is made.

Another object is to prepare a modified starch product which yields asofter cold paste than that of the unmodified starch.

A further object of this invention is to produce a modified starchproduct having the above listed properties by a method which does notdisrupt the starch granules through gelatinization. In the process ofthis invention, H

starch slurries are treated under conditions especially suited toequipment common to the industry.

Prior art has disclosed that starch may be modified by treatment withaluminum chloride. in this instance, modified starch products are formedwhich yield lower viscosity pastes than obtained from the unmodifiedstarch from which they were prepared. According to the presentinvention, treatment of starch with stannic chloride producesa,,modified starch product having quite different properties than thealuminum chloride modified starch. 'ihe stannic chloride modified starchof the present invention yields higher paste viscosities than obtainedfrom the unmodified starch.

Briefly, the present invention comprises reacting a relatively smallamount of stannic chloride with unmodified starch, as obtained from cornand preferably in the form of a slurry under controlled conditions.Control of the pH, and concentration of stannic chloride are criticalwhereas control of the temperature and time of reaction and the Baurn ofthe starch slurry are of minor importance.

in following the teachings of the present invention, a starch slurry,i.e., unmodified corn starch granules and water at a temperature ofabout 68 -l30 F. and with a Baum of 14 to 2.1, is acidified or madealkaline to adjust the pH thereof to preferably between 3 to 9. Thestarting pH of the slurry is usually in the neighborhood of about 3-5and will depend upon the source of the corn, the time of the year of itsharvest and conditions in the plant which produces the starch slurry.Any base or acid may be used which will adjust the pH to the requiredlevel such as sodium carbonate, (Na CO hydrogen chloride (l-lCl) or thelike. It is emphasized that the base or acid is not added for thepurpose-modifying the starch but in order to adjust the pH of the slurryin preparation for the addition of the reactant.

The amount of stannic chloride added for modification may vary from0.05% to about based on dry substance starch. With 0.05% of stannicchloride, a significant increase in viscosity is noted, especially inthe maxi- Patented Jan. 14, 196% mum alkaline viscosity (MAV). As morestannic chloride is reacted with the starch, the viscosity of themodified starch increases. As already indicated, the reaction can beconducted at a pH level above about 3 and up to about pH 9. Veryexcellent results are obtained when the pH range is 4-5 and this rangeis preferred. Since the stannic chloride is acidic in reaction, it maybe necessary to add an alkaline-reacting neutralizing agent to maintaina pH greater than 3. Ammonium, alkali metal, and/ or alkaline earthmetal hydroxides or carbonates may be employed as the neutralizingagent.

The reaction proceeds satisfactorily at temperatures of about 68 F. toabout 130 F. and is not extremely sensitive to temperature variation.Starch slurries at about F. as delivered to the drying equipment instarch plants work very satisfactorily in the process.

The reaction time may vary over a wide range. Starch slurries reactedfrom A1 to 10 hours or more before being sent to the driers have beenfound to be satisfactory. Occasionally, it is not possible to dry areacted starch immediately and the delays of 10 hours or more have notcaused any change in the viscosity of the modified starch.

The starch may be treated in the form of a slurry as it comes from thefinal stage of the wet milling process. The slurry may have almost anydensity. When slurries of 14 to 21 Baum have been treated underotherwise similar conditions, the resultant viscosities and otherproperties of the products are substantially the same.

After treating with the stannic chloride the slurries are filtered, andthe starch is dried at about 240 'F., for example, to about 10%moisture.

The measurement of the viscosity of hot starch pastes is used in theindustry to determine the degree of modification of starch products. Hotpaste viscosity is commonly determined by the Scott method and the CornIndustries Viscometer method. Procedures for these methods of analysisare described by R. W. Kerr in his book entitled Chemistry and Industryof Starch (Academic Press, Inc. of New York).

in addition to these tests, the maximum alkali viscosity (MA-V) has beenemployed to show the results of the reaction. In this test, 170 grams ofstarch (as is basis) is mixed with 900 ml. of water at F. and 100 ml. of32% sodium hydroxide solution. This mixture is placed in asteam-jacketed vessel equipped with a mechanical with a mechanicalagitator. Agitation is started and the temperature of the mixture israised to F. After holding at this temperature for 10 minutes, 900 ml.of tap water at 80 F. is added to the cooked starch paste. The mixtureis cooled to 100 F. and the viscosity is measured by means of aBrooloield viscometer.

The following examples further illustrates the process of the invention.

The processes, as described below, are applied to corn starch. However,these processes are also suitable for modifying other starches, such aspotato, tapioca, rice, grain, sorghum and wheat starches.

EXAMPLE 1 A corn starch slurry sample of 17 B. corrected to 0 F. wasseparated into two equal parts. The first part was used as a control. Tothe second part, 0.05%, dry substance basis (13.3.33), of stanaicchloride in an aqueous solution of about 30% concentration was added.The pH was adjusted to 4 and the slurry was held at 100 F. for 3 hours.Thereafter, the slurry was filtered and the starch was dried at 240 F.to a 10% moisture content. The control was subjected to the sametreatment, but Without the stannic chloride addition. The properties ofthe modified and control starch are set forth in Table I below.

Table I pastes was increased, reaching a maximum at the 15% stanriicchloride treatment level. viscosity (3) Set back on cooling as measuredby the aged paste 35: gfviscosity, was significantly lowered. Maximumlowering .n Example chloride, 0. Max. Vise. A.P.V., of this property wasreached at the 510% starinic chlo- Perm 73 72 ride treatment level.

(4) The maximum alkali viscosity was much higher I L Control 0 86 M0 1201,668 L200 than the controls at all leveis of treatment.

0. c5 $5 14 120 1,660 2,000 tarches with these nigher viscosities arespecially useful for adhesives, corrugating, charcoal, coal and oresMaximum viscosity, viscosity at 30 minutes and aged Iln'iluel-tmg texmefinishing Such as back Sizing fining pasta viscosity (ARV) were measuredin gr2m/Cenfi certain kind of fabrics 1n textile, wet end addition inmeter with Com Industries Rgsgarch Foundation paper manufacturing,acoustical tfle manutacturing, etc. cometer Maximum alkaline viscosi y(MAV) was EXAMPLES 14-17 measured in centipoises with Brookfieldviscometer as L described above. 1 The influence of pH on the processset forth in Ex- Tre-atment of starcn W1th 0.05% stanrnc chloride didample 1 was determined by treating 17 B. starch slurries not measurablyinfluence tnc viscosity characteristics of with 0.5% D.S.B. stannicchloride at 100 F. for 3 hours the starch wnen paste d Wlttl Watfil.However, under the at pH levels of 3-9. The results are set forth inTable alkaline conditions or the M.A.V. test, the viscosity was 0 IIIand show that reaction pH has little influence on the significantlyincreased. nature of the product obtained.

Table III Viscosity Cone. of

stannic p11 Gel. sample chloride, temp, Max. Visc. M.A.V.

percent vise, A.P.V. cps. Scott qnL/cm qm./cm. qm./cni

Con trol (14- 17). 0 87 130 120 1,120 1,120 as 14 0.5 3.0 81.5 105 100840 10,000+ 182 1s 0.5 5.0 80.5 212 100 850 10, 000+ is 0.5 7.0 80.5 230175 sec 10,000+ 200 17- 0.5 0.0 51.0 203 105 800 10, 000+ EXAMPLES 2-13The process set forth in Example 1 was repeated with 4 (11-25%concentrations of stannic chloride to determine the influence of theconcentration of this reactant on the properties of the final product.The properties of the modified starch products (Examples 2-13) and ofthe unmodified controls for these samples are presented in Table II.

Table II Viscosity Cone. of Gel. Example stannic temp,

chloride, C. Max Visc. A.P.V., percent Visc., 30', q1D./CH1.

qmJcm. qm./cm.

0 80 115 1, 500 1, 120 0.5 77 183 1, 400 10. 000+ 1.0 73 23 185 1, 12010, 000+ 2.0 68 400 200 1, 040 10, 000+ 5. 0 66 430 340 360 10, 000+ 1010.0 65 480 380 4A0 10, 000+ Control (ll- It will be seen from the abovetable that the following modifications in viscosity'properties haveoccurred:

(1) The gelatini'zation tem "erature was lowered 220 =C. below that ofthe control samples. The gelatinization temperature reached a minimum insamples treated with .5-10% stannic chloride.

(2) .In all cases the maximum viscosity of the hot EXAMPLES 18-22Examples 18-22 were conducted substantially as Example 1 on a 17 B.starch slurry, with 0.5% D513.

stannic chloride at a pH of 4 and at various temperatures as indicatedin Table IV.

Table IV 45 Viscosity Example Temp, Gel.

1 Temp, Max. Visc., A.P.V., C. Visc 30', qmJem. 5O qinjcrn. qin/crn.

:Tlie process has also been conducted at various reaction times but nosignificant differences in results have been noted between about A1 toover 6 hours of reaction time.

Similarly, changing the B. of the slurry has been found to have nosignificant effect on the results.

The following examples illustrate how the carried out in pilot plantquantities.

EXAMPLE 23 process is 40 gallons of B. final corn starch slurry from anddried. The results are set forth below in Table V.

Table V Viscosity Cone. of Visa, Example stannic Gel. Max.

chloride, Temp., Vise, qmJcm. A.P.V., M.A.V., Scott percent C. qrn./cm.qm/crn cps Control (23) O 87 110 1, 600 1, 240 82 23 -c 0. 5 79 230 1,320 10, 000+ 168 Control (24 O 85. 5 150 115 1, 580 1, 340 90 24 0. 5 78270 185 1, 260 10, 000+ 159 EXAMPLE 24 2. The process as claimed inclaim 1 wherein the re- 40 gallons of 18 B. corn starch slurry(containing about lbs. of starch) Were reacted with 350 g. of stannicchloride as in Example 23. A first portion of the run was filtered anddried after 1 hour and a second portion was held for 8 hours prior tofiltering. There was no significant difference between the two portions.The properties of the product are shown in Table V.

The features and principles underlying the invention described above inconnection with specific exemplifiestions will suggest to those skilledin the art many other modifications thereof. It is accordingly desiredthat the appended claims shall not be limited to any specific feature ordetails thereof.

We claim:

1. The process for producing a modified starch product, which yields ahigher than normal cooked paste viscosity, comprising reactingunmodified starch with 0.05 to 25% stannic chloride at a pH range ofabout 3 to about 9.

action is carried out at a temperature at about 68- l30 F.

3. The proces as claimed in claim 1 wherein said starch is in aqueousslurry and is treated under non-gelatinizing and non-swellingconditions.

4. The process as claimed in claim 3 comprising filtering and drying themodified starch.

5. A stannic chloride modified starch having increased paste viscosity,lower gelling temperature, and softer cold paste properties than theunmodified starch from which it is prepared by reaction with 0.05 to 25%of stannic chloride.

References Cited in the file of this patent UNITED STATES PATENTS1,984,246 Beyer Dec. 11, 1934 2,328,537 Felton et al. Sept. 7, 19432,468,207 Kerr Apr. 26, 1949

5. A STANNIC CHLORIDE MODIFIED STARCH HAVING INCREASED PASTE VISCOSITY,LOWER GELLING TEMPERATURE, AND SOFTER COLD PASTE PROPERTIES THAN THEUNMODIFIED STARCH FROM WHICH IT IS PREPARED BY REACTION WITH 0.05 TO 25%OF STANNIC CHLORIDE.